JP2003318426A - Photoelectric converter and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable photoelectric converter by relieving difference of thermal expansion of a material of substrate, a material of insulation layer and crystalline semiconductor particle with plastic deformation of aluminum (Al) and suppressing generation of warpage and crack. <P>SOLUTION: The photoelectric converter comprises a large amount of crystalline semiconductor particle 5 of a first conductivity type provided on a substrate as one electrode layer, an insulation substance 4 provided in the space among the crystalline semiconductor particle 5 and a semiconductor layer 5 of a second conductivity type formed on the crystalline semiconductor particle 5. The substrate 1 is formed of an aluminum substance 2 and this substrate 1 is moreover formed at least of two layers of an alloy layer 3 which is mainly composed of aluminum (Al) and silicon (Si) and the aluminum (Al) substance layer 2. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device used for photovoltaic power generation and a manufacturing method thereof, and more particularly to a photoelectric conversion device using crystalline semiconductor particles and a manufacturing method thereof.

[0002]

2. Description of the Related Art A conventional photoelectric conversion device using crystalline semiconductor particles is shown in FIGS. As shown in FIG. 2, in US Pat. No. 4,514,580, an aluminum film 12 is formed on the surface of a steel substrate 11, and the aluminum film 1 is formed.
There is disclosed a photoelectric conversion device in which pulverized silicon particles 13 are bonded to 2 and an insulator layer 4, an n-type silicon portion 14, and a transparent conductive layer 15 are sequentially formed.

Further, as shown in FIG.
In Japanese Patent No. 24179, an opening is formed in a first aluminum foil 21, and a silicon sphere having an n-type skin portion 23 on a p-type silicon portion 22 is bonded to the opening to form an n-type on the back side of the sphere. The skin 23 is removed, the aluminum foil 21 is coated with an oxide layer 24, and the p-type silicon portion 2 on the back side of the ball is removed.
There is disclosed a photoelectric conversion device in which the oxide layer 24 in the vicinity of 2 is removed and the second aluminum foil 25 is bonded.

Further, as shown in FIG. 4, Japanese Patent No. 26418
No. 00 discloses a low melting point Sn on a stainless steel substrate 32.
The layer 31 is formed, the crystal semiconductor particles 5 of the first conductivity type are disposed on the Sn layer 31, and the second semiconductor layer 5 is formed on the crystal semiconductor particles 5.
A photoelectric conversion device is disclosed in which a conductive semiconductor layer 6 is formed between the semiconductor layer 6 and the Sn layer 31 with an insulating layer 4 interposed therebetween. In addition, in FIG. 4, 7 is a transparent conductive film.

[0005]

However, in the photoelectric conversion device of US Pat. No. 4,514,580 shown in FIG. 2, the aluminum film 12 is formed on the surface of the steel substrate 11 as a substrate.
To form the insulating layer 4 and the crushed silicon particles 1 on the substrate 11.
3 is arranged, and when a glassy layer is selected as the insulating layer 4, warpage may occur in the substrate 11 during the manufacturing process due to the difference in the thermal expansion coefficient between the substrate 11, the insulating layer 4, and the crystalline semiconductor particles 12. Further, there is a problem that cracks occur in the crystalline semiconductor particles 13 and the insulating layer 4 due to the temperature cycle under the use environment.

Further, Japanese Patent Laid-Open No. 61-2417 shown in FIG.
In the photoelectric conversion element disclosed in Japanese Patent Publication No. 9, an aluminum foil 21 is used as a substrate, and an insulating layer 2 made of oxide is formed on the substrate 21.
4 and the p-type silicon portion 22 are arranged, and similarly, there is a problem that the warp of the substrate 21, the p-type silicon portion 22 and the insulating layer 24 are cracked.

In the photoelectric conversion device of Japanese Patent No. 2641800 shown in FIG. 4, a Sn layer 31 having a low melting point is formed on a substrate 32 made of stainless steel, and the insulating layer 4 and the first conductivity type are formed on the substrate 32. In the same manner as described above, there is a problem that the warp of the substrate 21, the p-type silicon portion 22 and the insulating layer 24 are cracked.

The present invention has been made in view of the above problems in the prior art, and an object thereof is to reduce the difference in thermal expansion between the material of the substrate, the material of the insulating layer and the crystalline semiconductor particles of aluminum (Al). An object of the present invention is to provide a highly reliable photoelectric conversion device that is relaxed by plastic deformation and suppresses warpage and cracks.

[0009]

In order to achieve the above object, according to the photoelectric conversion device of the present invention, a large number of first-conductivity-type crystalline semiconductor particles are provided on a substrate to be one electrode layer. In a photoelectric conversion device in which an insulating material is interposed between the crystalline semiconductor particles and a semiconductor layer of the second conductivity type is formed on the crystalline semiconductor particles, the substrate is made of aluminum having a purity of 98% or more, and An alloy layer containing aluminum (Al) and silicon (Si) as main components is formed on the surface of the substrate.

In the above photoelectric conversion device, the substrate thickness is preferably 0.1 mm or more.

In the above photoelectric conversion device, it is desirable that the insulating material is glassy.

In the method for manufacturing a photoelectric conversion device according to a fifth aspect of the present invention, a large number of crystal semiconductor particles are arranged on an aluminum substrate, the aluminum substrate and the crystal semiconductor particles are heat-welded, and aluminum (Al) is attached to the welded portion. And silicon (S
It is characterized in that an alloy layer containing i) as a main component is generated.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. The present invention is not limited to the following examples, and modifications and improvements can be made without departing from the spirit of the present invention.

FIG. 1 is a diagram showing an embodiment of a photoelectric conversion device of the present invention, in which 1 is a substrate, 2 is aluminum, 3 is an alloy layer of aluminum and silicon, 4 is an insulating material, and 5 is crystalline semiconductor particles. , 6 is a second conductivity type semiconductor layer, and 7 is a protective layer.

Here, the aluminum 2 having a purity of 98% or more is used. If the aluminum purity is lower than 98%, the proof stress, which is a physical property of the material, increases and it becomes difficult to plastically deform, and the substrate 1 is warped due to the difference in thermal expansion coefficient between the substrate 1 and the insulating material.

The substrate 1 is formed with an alloy layer 3 containing aluminum (Al) and silicon (Si) as main components by welding crystalline semiconductor particles 5 made of silicon (Si) to one surface layer of the aluminum layer 2. Then, the substrate 1 having the aluminum 2 part and the alloy layer 3 part is obtained. Aluminum (A
l) a barrier layer for controlling the generation of the alloy layer 3 of aluminum (Al) and silicon (Si) at the boundary between the alloy layer 3 mainly containing silicon (Si) and the aluminum (Al) layer 2. It is also possible to provide an optional thin intermediate layer (not shown).

The thickness of the substrate 1 is preferably 0.1 mm or more. If the thickness of the substrate 1 is smaller than 0.1 mm, it is difficult to form the substrate 1 having two or more layers of the alloy layer 3 containing aluminum (Al) and silicon (Si) as main components and the aluminum (Al) layer 2. Therefore, it is not preferable. The thickness of this substrate 1 is preferably 0.2 mm or more. The insulator 4 is made of an insulating material for separating the positive electrode and the negative electrode. For example, an insulator using glass containing silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), lead oxide (PbO), boron oxide (B ₂ O ₃ ), zinc oxide (ZnO), etc. as an arbitrary component. Etc.

The first conductivity type crystal semiconductor particles 5 are made of silicon (S
i) p-type boron (B), aluminum (A)
1), gallium (Ga), etc., or phosphorus (P), arsenic (As), etc. exhibiting n-type are contained in trace elements. The crystal semiconductor particles 5 may have a polygonal shape, a curved surface, or the like. The grain size of the crystalline semiconductor particles 5 is preferably 0.1 to 0.6 mm, and if it exceeds 0.6 mm, silicon (Si) of the conventional crystal plate type photoelectric conversion element is used.
The amount is the same as the amount used, and the merit of using crystalline semiconductor particles is reduced. On the other hand, if it is smaller than 0.1 mm, the light energy loss such as light transmission increases, and the photoelectric conversion efficiency decreases.

The second conductivity type semiconductor layer 6 is introduced by a vapor phase growth method or the like, for example, by introducing a small amount of a vapor phase of a phosphorus compound which exhibits an n-type or a vapor phase of a boron compound which exhibits a p-type to the vapor phase of a silane compound. To form. The second conductive semiconductor layer is made of silicon, silicon carbide, germanium or the like. The semiconductor layer 6 may be amorphous, single crystalline, polycrystalline, or microcrystalline. The concentration of the trace element in the semiconductor layer 6 is, for example, 1 × 10 ¹⁶ to 10 ²¹ atm / cm ³
It is a degree. The film thickness is preferably 10 nm or more and 500 nm or less. When the film thickness is 10 nm or less, leakage due to film defects increases and conversion efficiency decreases, which is not preferable. When the film thickness is 500 nm or more, light absorption of the second conductivity type semiconductor layer 6 increases and conversion efficiency decreases. Therefore, it is not preferable.

It is preferable that the protective film 7 has a characteristic of a transparent body, for example, tin oxide, zinc oxide, indium oxide, titanium oxide, silicon oxide, cesium oxide, aluminum oxide, silicon nitride, titanium oxide, tantalum oxide, yttrium oxide. CV with a single composition or multiple compositions in a single layer or in combination
It is formed on the semiconductor layer 6 by the D method, the PVD method, or the like. Since the protective film 7 is in contact with the light incident surface, it needs to be transparent. If the thickness of the protective film 7 is optimized, the function as an antireflection film can be expected.

It is also possible to improve the conversion efficiency by providing pattern electrodes such as fingers or bus bars at regular intervals on the semiconductor layer 6 or the protective film 7 in order to reduce the series resistance value.

Next, the manufacturing method of the present invention will be described in the order of steps. First-conductivity-type crystalline semiconductor particles 5 on an aluminum substrate
And a first conductivity type crystal semiconductor particle 5 and an aluminum substrate are welded to each other by heating at 580 ° C. to 660 ° C. for 1 to 20 minutes, and aluminum (Al) and silicon (S
An alloy layer 3 containing i) as a main component is formed. When the first conductivity type crystalline semiconductor particles 5 are arranged on an aluminum substrate,
In order to fix the first-conductivity-type crystal semiconductor particles 5, it is possible to interpose a resin or the like between the aluminum substrate and the first-conductivity-type crystal semiconductor particles 5 and heat-weld them.

After that, the insulating material 4 is filled and formed between the first-conductivity-type crystalline semiconductor particles 5 having a height such that the lower surface side is filled, and then baked and solidified. In order to promote plastic deformation of the aluminum substrate, it is also possible to mechanically add weight so as to suppress substrate warpage during firing of the insulating material. Further, the insulating material 4 is vitreous, and the vitreous substance may be a mixed system of inorganic and organic components.

After that, the second conductivity type semiconductor layer 6 and the protective film 7 are formed.
Are sequentially formed to manufacture the photoelectric conversion device of the present invention.

[0025]

EXAMPLES Next, examples of the photoelectric conversion device of the present invention will be described. As shown in Table 1, an aluminum (Al) substrate having a size of 150 mm × 150 mm and several kinds of thickness is prepared, and a large number of p-type silicon particles having a diameter of about 0.3 mm are arranged on the substrate, and the temperature is set to 600 ° C. The silicon particles are bonded to the substrate 1 by heating for 10 minutes, and aluminum (Al) and silicon (S
A substrate 1 having an alloy layer 3 containing i) as a main component and an aluminum (Al) layer was prepared. A glass paste was used as an insulating layer so as to have a thickness of about 150 μm between silicon particles, and the substrate 1 was fired with a weight applied to it for plastic deformation. The glass used for the glass paste had a softening temperature of about 500 ° C. Then, an n-type amorphous silicon layer having a thickness of about 40 nm was formed on the silicon particles and the insulating layer, and a zinc oxide film was further formed as a protective film.

The warp of the sample produced as described above and the initial stage and the crystalline semiconductor particles and the glass insulating layer after the temperature cycle of −40 ° C. to 90 ° C. for 200 cycles were observed with a 100 × binocular microscope for cracks. If there is a crack, it is ×, if there is no crack, it is ○,
The results are shown in Table 1.

[0027]

[Table 1]

Sample No. In the No. 1 and No. 2 substrates, the warpage amount was extremely large at 17.1 to 18.6 mm, many cracks were generated in the glass insulating layer, and peeling of the glass insulating layer was also partially generated. Sample No. The warpage amount of 3 and 4 is 6.
Although it was slightly large at 5 to 9.2 mm, cracks in the glass insulating layer could not be confirmed both at the initial stage and after the temperature cycle. on the other hand,
Sample No. In Nos. 5 to 9, the amount of warpage could be suppressed to a very small value of 5 mm or less, and cracks in the glass insulating layer could not be confirmed both at the initial stage and after the temperature cycle.

From this, it was confirmed that the photoelectric conversion element of the present invention was a photoelectric conversion device capable of maintaining high reliability. Note that the above is merely an example of the embodiment of the present invention, and the present invention is not limited thereto, and various modifications and improvements may be added without departing from the gist of the present invention. .

[0030]

As described above, according to the photoelectric conversion device of the present invention, a large number of first-conductivity-type crystal semiconductor particles are provided on the substrate which is one of the electrode layers, and between the crystal semiconductor particles. In a photoelectric conversion device in which a semiconductor layer of the second conductivity type is formed on the crystalline semiconductor particles with an insulating material interposed, the substrate is made of aluminum, and the difference in thermal expansion between the aluminum substrate and the insulating material is aluminum (Al). It is possible to provide a photoelectric conversion device that can be relaxed by the plastic deformation, suppress the warp amount of the substrate, and prevent the generation of cracks in the crystalline semiconductor particles and the insulating layer due to the temperature cycle.

According to the method for manufacturing a photoelectric conversion device of the present invention, a large number of crystal semiconductor particles are arranged on an aluminum substrate, the aluminum substrate and the crystal semiconductor particles are heat-welded, and aluminum ( Since an alloy layer containing Al) and silicon (Si) as main components was generated,
The difference in thermal expansion between the aluminum substrate and the insulating material is mitigated by plastic deformation of aluminum (Al), and the warpage amount of the substrate is suppressed,
It is possible to provide a photoelectric conversion device capable of preventing the generation of cracks in the crystalline semiconductor particles and the insulating layer due to the temperature cycle.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment of a photoelectric conversion device of the present invention.

FIG. 2 is a cross-sectional view showing an example of the form of a conventional photoelectric conversion device.

FIG. 3 is a cross-sectional view showing another example of the form of a conventional photoelectric conversion device.

FIG. 4 is a cross-sectional view showing another example of the form of a conventional photoelectric conversion device.

[Explanation of symbols]

1 ... Substrate 2. Aluminum layer 3 ... Alloy layer 4 ... Insulator layer 5 ...
・ First conductivity type crystalline semiconductor particles, 6 ... Second conductivity type semiconductor layer, 7 ... Protective layer

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5F051 AA02 AA03 BA18 CA20 CB12                       CB13 CB29 CB30 DA02 DA09                       EA18 FA06 GA02 GA06 GA20                       HA03

Claims (5)

[Claims] 1. A large number of crystal semiconductor particles of the first conductivity type are provided on a substrate to be one electrode layer, an insulating material is interposed between the crystal semiconductor particles, and a second semiconductor is formed on the crystal semiconductor particles.
In a photoelectric conversion device having a conductive semiconductor layer, the substrate is made of aluminum having a purity of 98% or more, and aluminum (Al) and silicon (Si) are formed on the surface of the substrate.
A photoelectric conversion device, wherein an alloy layer containing as a main component is formed. 2. The photoelectric conversion device according to claim 1, wherein the substrate thickness is 0.1 mm or more. 3. The photoelectric conversion device according to claim 1, wherein the insulating material is glassy. 4. The crystalline semiconductor particles have a particle size of 0.1 to 0.1.
It is 0.6 mm, The photoelectric conversion apparatus of Claim 1 characterized by the above-mentioned. 5. A large number of crystal semiconductor particles are provided on an aluminum substrate, the aluminum substrate and the crystal semiconductor particles are heat-welded, and an alloy layer containing aluminum (Al) and silicon (Si) as main components is formed on the welded portion. A method for manufacturing a photoelectric conversion device, wherein the second conductive type semiconductor layer and the protective film are sequentially formed by generating the crystalline semiconductor particles and then filling the crystalline semiconductor particles with an insulating material.